Viscosity responsive apparatus



July 27, 1943.

T. D. THOMPSON Erm.

VISCOSITY RESPONSIVE APPARATUS 4 sheets-sheet 1 Filed NOV. 26, 1958 g +i u INV ENTORS. Caecz ATTORNEY.

vJuly 27, 1943 T. D. THOMPSON ETAL 2,325,573

VISCSITY RESPONSIVE APPARATUS 4 Sheets-Sheet 2 Filed Nov. 2e, 1958 ATTORNEY.

July 27 1943 T. D. THOMPSON ETAL i 2,325,573 l VISCOSITY RESPONSIVE APPARATUS Filed Nov. 26, 1938 4 Sheets-Sheet 3l INVETORS,

/zow fz July 27, 1943.

T. D. THOMPSON AL VISCOSITY RESPONSIVE APPARATUS Filed Nov. 2e, 19385 4 Sheets-Sheet 4 Vzefaf 1NVENTOR5,

earge BY ma@ /wr/zpa ATTORNEVY.

Patented July. 21, i943 vrscosrrr nnsronslva ArrAnArUs mannen Puk. N. J.. ma p assignors Thompson,

tosteimllailb Caesar, Staten Island, N. Y.,

Company,L Inc., New York, N. Y.,

a corporation of New York n Application November ze, 193s, sensi No. 24am n s claims (ci. 12v-za) This invention relates to a new and improved method and new and improved apparatus for controlling reactions `involving a variation in viscosity. v l

The commercial and technical need of some positive, compact and economical device to utilize viscosity or consistency as a means of processing control in a wide range of applications and to do 'it'automatically or semi-automatically is pressing. Various ingenious devices have been suggested and some of them have found useful 'special application. None of the known devices, to our knowledge, however, embraces the combination of positive controls and action peculiar to our invention as hereinafter described.

One of the objects of our inventionis to provide a new and improved means for controlling automatically or semi-automatically various types of chemical reactions.

Another object is to provide a new and improved combination of automatic processing controls operated by variations in viscosity.

Still a further object is to provide a new and improved means for processing starch and other amylaceous materials. Other objects will appear hereinafter.

In accomplishing these objects in accordance with this invention, we provide a combination of automatic controls for reactions involving a variation in viscosity which includes. a reaction vessel for holding the reaction mixture, a viscosity responsive means, means for circulating at least a portion of the reaction mixture in substantially` non-pulsating flow under conditions adapted to cause said viscosity responsive means to operate with changes in viscosity, and means controlled by said viscosity responsive means to cause said reaction to be controlled according to variations in viscosity. Additionally, we have provided means for controlling chemical reactions jointly by viscosity responsive means and thermal responsive means.

In the practice of our invention we have developed several dill'erent types of apparatus for controlling chemical reactions in response to changes in viscosity. One lof these types of apparatus, as hereinafter more fully described, is particularly advantageous for use where delicate control of chemical reactions in response to viscosity is desirable. 'I'his type of apparatus involves the use of a viscosity responsive means comprising a flexible diaphragm which is responsive to the pressure created by changes in viscosity of at least a portion of the reaction huid circulating atan approximately constant rate ol' ilow,` the variation in pressure a function ottheviscosityorconsistencyottheiimdand the diaphragm being so arranged and constructed as to cause suitable relays or other motor actuated means to operate and thereby to control the input ol heat and/or to add suitable quantities of liquids or chemicals for specific purposes.

Another type of' apparatus which we provide in accordance with this invention is adapted particularly for use in conjunction with chemical reactions where the control required is not affected by relatively small or minute changes in viscosity. In this type of apparatus changes in viscosity are translated to a combination of controls by a suitable torque mechanism associated with the circulating system as more fully hereinafter -described.

Other features and advantages of the invention will appear by reference to the accompanying drawings, in which:

Figure 1 represents ditically one type of apparatus constructed in accordance with the principles of the present invention;

Figure 2 represents diagrammatically a modiiled form of apparatus 'which may be employed in accordance with this invention; c

Figure 3 illustrates diagrammatically a wiring diagram to be used in conjunction with the construction shown in Figure 2; V

Figure 4 illustrates partly in cross-section and with parts cut away a modied form of a viscosity responsive means which may be employed in accordance with this invention; I Figure 5 illustrates diagrammatically another form of apparatus which may be employed in accordance with this invention and in which the control of reactions is effected by a viscosity responsive torque mechanism;

Figure 6 illustrates'in prole a portion of the on that portion of the apparatus as shown in Figure 8 and taken along the line 8 9 oi Figure 8.

'Ihe apparatus illustrated in Figure 1 comprises a reaction vessel 2 provided with a stirring device l. stirring device 4 is actuated by means of gears 6 and l connected by a drive shaft I0 to any suitable source of power,u as, for instance,

a motor or the like. Heat is supplied to reaction vessel 2 by means of a direct steam line I2 controlled by a valve I4 which, for the purpose of this invention, is preferably a solenoid valve or a motor actuated valve.

When a reaction mixture consisting of one or more substances in the form of a dispersion is introduced into vessel 2, a portion of said mixture may be recrculated from the bottom of vessel 2 through outlet I6 controlled by valve I8 into conduit 20, thence through a constant volume pump 22 and conduit 24 to a pressure viscosity controlunit 26. From the pressure viscosity control unit 26, the liquid is passed through conduits 28, 30 and 32, and returned to reaction vessel 2. A thermometer 34 is provided to indicate the temperature of the circulating :duid at any time. A second thermometer 36 may be provided to aid in the control oi the reaction. As

illustrated, the various portions of the recirculating system are readily removable from each other. For instance. the viscosity control unit 26 may be removed from conduits 24 and 28 simvply by unscrewing threaded unions 38 and 40.

Viscosity control unit 26 consists of a chamber 42 provided with a cap 44 and a flexible diaphragm 46, which is associated with a plunger 48. It will be understood that the size and shape of chamber 42 may be varied and if desired, it may conform generally to the dimensions oii conduits 24 and 28. v

Plunger 48 is associated with an arm 50 mounted on a fulcrum 52 and provided in any suitable manner with a Weight 54 by means of which pressure may be exerted downwardly against plunger 4B. The position of arm 58 and, correspondingly, the position of plunger 4B and of diaphragm 46 may be regulated to some extent by means of set screws 56, 66. Likewise the position of weight 64 on arm 58 may be regulated by sliding weight 54 from one position to another and iixing it in anyone position by means of set screw 60. The forked arm 62, which carries set screws 56, 66 is also associated with an electrical switch 64 which may be, for example, a mercury switch, so that movement of arm 50 transmitted to arm 62 serves to open and close said switch.

As will be seen by reference to the wiring diagram shown in conjunction with thev apparatus, valve I4 may be opened and closed by opening and closing switch 64.

Since switch 64 is automatically controlled by the movement of diaphragm 46, which in turn is responsive to changes in viscosity of the liquid being recirculated through the recirculating system, the supply of steam through valve I4 is directly controlled by changes in viscosity.

The operation of the apparatus is initiated by introducing the reacting materials into vessel 2 and starting agitator 4, then closing the main switch 66 and push button 68, thereby to complete a circuit for energizing in multiple the windings of magnetic valve i4 and relay lll. This circuit extends from the positive terminal of a suitable source of direct current supply, not shown, by way of conductor l2, through the windings of magnetic valve I4, conductor 14, contact 16., conductor 18, switch 68, conductor 8D, contact 82, conductor 84, mercury switch 64, conductor 86 to the negative terminal of said source of direct current and from conductor 88 through' the windings of relay 'I0 and conductor 90 to conlductor 18, switch 68, conductor 8D, contact 82,

conductor 84, switch 64 and conductor 86 to the negative terminal of the source of current.

When energizing over the circuits traced above, valve I4 is opened and permits the entry of a direct source of heat, such as steam, into vessel 2. Relay 10, which normally' makes contact between contacts 92 and 94, immediately breaks said contacts and makes contact with contacts 16 and 82, thus short circuiting push button switch 68 and causing the operation of steam valve I4 to become entirely automatic and depend only upon main circuit switch 66, which is normally closed, and mercury switch 64, which may be closed or open, depending upon the viscosity.

When the reaction mixture in vessel 2 has reached a suitable uidity, pump 22 is started and valve I6 is opened, thereby causing a portion of the reaction mixture to be circulated in a ooniined stream at constant volume, regardless of viscosity, through the circulatory system comprising conduits 26, 24, 28, 30 and 32. As the reaction fluid circulates, it passes through viscosity control unit 26 andvariations in viscosity cause variations in pressure upon diaphragm 46. Weight 54 is so adjusted that diaphragm 46k will not be raised or lowered, as the case may be, until a predetermined viscosity has been attained. Thus, if the reaction involves an increase in viscosity, weight 64 will be so adjusted that at predetermined viscosity the pressure caused by the liquid circulating through unit 26 will just be sumcient to raise diaphragm 46 and thereby raise arm 66 and cause switch 64 to open.

When switch 64 opens, it breaks the circuit through valve I4 and thereby causes valve I4 to close and at the same time causes relay 'ED to restore. When relay I0 restores across contacts 92 and 94, a new circuit is established from the positivey terminal of the source of current through conductor 88, conductor 96, contact 94, conductor 98, contact 92, conductor E00, electric signal IDZ, conductor 404 and conductor 36 to the negative terminal of the source of current. This causes signal 62 to give an alarm which may be a visible or audible alarm, and indicates that the viscosity has reached the desired predetermined point.

At this point the reaction may be completed or only partially completed, and further reacting materials may be added. The process may thereafter be repeated until the desired result has been reached.

The reaction may be one which involves a decrease in viscosity rather than an increase in viscosity, in which case the switcht, closing valve I 4, may be so arranged thatthe falling rather than rising of diaphragm i6 causes the opening of said switch.

If, in an operation of this type previously described, the viscosity increases so as to cause diaphragm 46 to rise and thereby' open switch 64 but then later decreases, the construction shown is such that switch 6d will be closed by the falling of diaphragm 46, in which case a circuit would again be completed through the windings of magnetic valve Id and said valve would again be open. At the same time the windings of relay 'I0 would be energized, breaking the circuit between contacts ,92 and 64 and closing the circuit between contacts I6 and 82.

A somewhat different arrangement is shown in Figure 2 in which vessel 164 is provided with a cap |06 and jacket |88. The reaction mixture III! is circulated through valve H2 by means of a constant volume pump II4 through a viscosity assuma responsive means ||6 of the character previously described and thence through a conduit ||6 past a thermal control means |26 to conduit |22, controlled by valve |24. From conduit |22 the recirculated mixture is returned to reaction vessel V|64 through opening |26. I! desired. instead of passing the mixture back into reaction vessel |64 it may be emptied into mother vessel or container by means oi conduit |26 controlled by valve |66. Ii 'it is desired to recirculate the mixture to the reaction vessel. valve |66 would normally be closed and valve |24 would be open,

vbut where the mixture is not to be recirculated,

valve |24 is closed and valve |36 is open, thus allowing the reaction products or reaction mixture to pass out through conduit |26.

As shown, in order to carry out the reaction, steam may be introduced through conduit |62 controlled by a motor actuated valve |64, such as, for example, a solenoid operated valve. An auxiliary steam line |66 runs to the Jacket |66 oi vessel |64 and may be opened and closed by an electrically operated valve such as a magnetic valve I 36. The amount of steam passing to the jacket of said vessel |64 may also be regulated by an auxiliary valve |46.

The purpose ot this type oi' apparatus is to provide a combination of means for controlling a reaction according to changes in viscosity or according to the temperature of the reaction mixture or for jointly controlling the reaction by variations both in viscosity and temperature.

'I'he operation oi' this form of apparatus may be illustrated by reference to the wiring diagram shown in Figure 3. As illustrated, the operation of the apparatus is initiated by closing a main switch |42 and push button' |44 thereby to keep a circuit for energizing in multiple the windings of magnetic valve |34 and relay |46. This circuit extends from a suitable source of-current through conductor |66 to mercury thermal switches |54A and 54B. Reference numerals |62, |64, |66 and |68 represent contact points of a two pole double throw relay. Normally, when no current is flowing. through coil |46 contacts |62 and |64 are connected through short circuiting bar A and form a continuous circuit through conductor |16, signal |16, conductor |14, magnetic valve |88 and conductor |12 to the other side of the line.- This forms a simple r thermal control circuit actuated in its entirety by mercury thermal switch |64B.

A companion circuit extends from switch |64A to contact |68 and to one terminal of a single pole push button switch |44. From contact |66 and one pole of the push bitton switch |44 the circuit extends to a pressure actuated mercury switch ||6 generally illustrated in Figure 2. It will be understood Athatthe diaphragm apparatus generally illustrated at I I6 o! Figure 2 may be substantially the same or similar to viscosityA control' unit 26 described in connection with Figure 1. From mercury switch |52 the aforesaid circuit extends through conductor |66, magnetic valve |34 and conductor |46 to the other side of the line. This circuit is inactive until push button switch |44 is closed, whereupon current nows through switch |44, conductor. |66 and the coil of relay |46 to conductor |66 which connects to the other side of the line through conductor |48. Thus, closing push button switch |44 energizes coil |46 thrusting short circuiting bar A against contacts |66 and |66 whereupon push button |44 becomes inactive and may be relayed. As will be seen in the diagram, the

-steam valve |38,

. nected to diaphragm 262 circuit is now continuous from conductor |66 through thermal switch |64A, relay contacts |66 and |66, pressure actuated switch |62, conductor' |66 and masneticwalve |64 to the other side of the line represented by conductor |46. `As long as this circuit is not broken, valve |64 remains clzin and steam is admitted to reaction vessel In the meantime, a portion of vreaction mixture I6 is constantly and uniformly circulated from the bottom ot reaction vessel |64 through valve ||2, pump ||4, viscosity responsive apparatus -||6, conduit ||6, valve |24 and conduit |22, from whence it is returned to the reaction vessel through opening |26.

will change from time to time as the .reaction continues. For any particular reaction the dla- When the viscosity of the reaction mixture issuch that there is suillcient pressure to actuate diaphragm mechanism H6, diaphragm switch 62 of Figure 3 is opened, thus breaking the circuit through magnetic v'alve |34 and shutting 01T the steam from reaction vessel |64. As soon as the viscosity falls to a point which lowers the pressure suiiiciently to permit closing of viscosity responsive switch4 |52, the circuit through magnetic valve |34 is again closed, causing said valve to open. Should at any time during the operation the temperature rise to a point where mercury switch |54A is opened, then the entire circuit is broken, magnetic valve |34 closes'and short circuiting bar A falls back to its normal position across contacts |62 and |64. This circuit then remains inoperative yuntil push button |44 is again closed, repeating the cycle.

The other side of the circuit which is in operation when contacts |62 and |64 are closed by short circuiting bar A, is now operative and is v of thermal actuated switch 54B. Switch |54B.

as it opens and closes, opens and closes magnetic which in turn controls the admission of steam to jacket |68.

An alternate type of viscosity responsive means which may be employed in accordance with this invention is illustrated in Figure 4 and comprises a conduit 266, a iiexible diaphragm 262 supported by supporting means 264 and by a cap 266 having therein an aperture 268. Conis an arm 2|6 which is associated at the other end with a balance arm 2|2 and may be adjusted with respect to said balance arm by means of a set screw 2|4. Balance arm 2| 2 has a depending portion 2|6 which is connected by means of a pin 2|8 to a projecting portion 226, associated with 'a base plate 222. As will readily be seen, pin 2| 6 acts as a fulcrum for balance arm 2| 2. `At `one end balance arm 2|2 is provided with counterweight 224 having a set screw 226. At the other end it is provided with a depending weight 226 to which other weights 2,36 may be'added in order to build up any desired amount of pressure on diaphragm 262.

An approximately constant volume of liquid circulating through conduit -266 is approximately angential to and in contact'with diaphragm 62. increases to such a point that the pressure ,exerted against diaphragm 262 is greater than the As this portion o1.'4 the reaction mixture i5 recirculated its viscosity Hence, when the viscosity of such liquid.

downward pressure caused by weights 230, diaphragm 202 will be forced upwardly and this in tm'n ycause arm 2I0 to be forced upwardly and will raise arm 2I2.

Arm 2i2 is associated with a switch 232 which may be, for example, a mercury switch, so that when said switch is tilted, a contact is broken.

Thus, switch 232 takes the place of Switch |52 I in the apparatus described in Figures 2 and 3 and takes the place of switch 64 in the apparatus in Figure 1.

It will be understood that other variations may be made in the apparatus described Without departing from the invention. For instance, in Figurev 1, a switch may be associated with thermal responsive means 36 and connected in series with switch 64. In this way valve I4 may be regulated or controlled both by the viscosity of the by the use of an auxiliary conduit, not shown, controlled by an electrically operated valve which occupies substantially the same position in the circuit illustrated in Figure l as electrically operated signal |02. Thus, when the viscosity or the temperature becomes too high, thereby causing valve I4 to close and relay 10 to restore, an auxiliary valve of the type described would be opened to introduce a predetermined quantity of Water,

or other material. All circuits herein describedr may be adapted for operation with either direct or alternating current. Similarly, other variations may be made without departing from the invention.

Referring to Figure 5, the apparatus illustrated comprises a reaction vessel 300 provided with a jacket 302 and a top 304. Vessel 300 is adapted to` hold a reaction mixture 306. A portion of this mixture may be recirculated continuously or atI intervals through a reclrculating system comprising a valve 308, a conduit 3I0, a pump land torque mechanism generally illustrated at 3 I2 and shown in more detail in Figure 6, and conduit 3| 4. Conduit 3I4 returns the circulated fluid to the reaction vessel through opening 3I6. Steam is supplied to the reaction vessel through conduit 3I8 which is controlled by an electrically operated valve 320 and a mechanically operated valve 322. Conduit 318 leads to a source of steam not shown. Connecting conduit 3| 8 with jacket 302 is a conduit 324 controlled by an electrically operated I valve 326.

The pump and torque mechanism shown generally at 3I2 in Figure 5 and illustrated more specifically in Figure 6 comprisesl a motor 328 connected -through a suitable reduction gear box 330 to a torque mechanism 332 and a pump 334. Conduit 3I0 of Figure 5 is connected to one side of pump 334 and conduit 3I4 to another side. Motor 328, vreduction gear box 330, torque mechanism 332 and pump 334 may, ifdesired, all be mounted upon a common base 336.

Thetorque mechanism is illustrated more specifically in Figures 8 and 9. As shown in Figure 9, pump shaft 338 and motor shaft 340 If ythe temperature becomes too high, the

are concentric and gear box 342 contains. six gears, 344, 343, 343, 351i, 352 and 354. All of lthese gears are run on regular thrust ball bearings such as illustrated at 356, and are enclosed in a bronze case in which they are immersed in oil. Figure 8 shows the complete mechanism in cross-section along the line of the pump and motor shafts except that steam valve 322 is not shown.

As illustrated in Figure 8, gear case 342 is free to move around the drive shaft of the motor and pump 338 and 340, respectively. 'I'he amount of movement is regulated by spaces 356 and 358 in members 360 and 362, respectively, which are mounted on a suitable base 364. As illustrated, gear case 342 is connected at its extremities 365 and 368 to members 310 and 312, which in turn are connected to a supporting bar 314 containing a counter balance or weight 316, which is adapted to move on said bar and is adjustable by means of a set screw 318. Mounted on member 312 is a connecting member 388 which, as shown in Figure 5, is connected by means of a pin or other suitable means to a connecting rod 382. Connecting rod 382 in turn is pivotaily connected to connecting rod 384, which in turn is connected to valve 322.

to valve 322.

I'he operation oi this apparatus is based upon the principle that the torque imparted to gear oase 322 by rotation of the six gears therein caused by motor 328 will vary with changes in viscosity of the reaction mixture being pumped through pump 334. This variation in torque causes the gear box 342 to move clockwise or counterclockwise, as the case may be, and this movement is translated to steam valve 32 2 in the manner previously described. In this way control of the chemical reactions in vessel 300 is made responsive -to the viscosity. It will be understood, of course, that it is not absolutely essential that valve 322 be a mechanically operated valve. It may be an electrically operated valve actuated by a switch, which in turn is actuated by movement of gear box 342. Other changes may be made in the apparatus described without departing from the invention. This form of apparatus is particularly adapted for the processing of very heavy starch mixtures, although it may be used in .many other applications. The apparatus described with reference to Figures l to 4,

on the other hand,Y is especially adapted for chemical reactions where there is a relatively low concentration of reactants.

In addition to the viscosity responsive control means previously described we preferably provide the apparatus of Figure 5 with a thermal responsive means adapted to control the reaction according to operating temperature conditions. The operation of the thermal responsive means may be illustrated by reference to Figure '7 in which thermal switch 386 is controlled and operated by thermocouple 388, the later being in contact with the recirculating reaction mixture carried in conduit 3 I4.

As shown in Figure 7, the wiring diagram includes a relay 330 and the two magnetic valves 320 and 326 also shown in vFigure 5. The electrical circuit of Figure 7 is controlled by two switches, a main line swtich 392 and a push button switch 394. In normal position short circuiting bar B of relay 390 connects contacts 396 and 398, thus establishing a circuit from a source of electrical current, not shown, through switch Thus, any movement of gear case 342 is,` translated through connecting rods 382 and 384 switch 3,

-ing push button assura 332, conductor Ill, thermal switch 3, conductor 432,-contacts 390 and 333, conductor C and the coils ot valve 323 to conductor l on the other side of ithe line. Thus, in normal position valve 326 is open and is controlled entirely by thermal switch 33C.

A companion circuit from a source of current through switch 332, conductor "I, thermal conductor 3. switch 334, conductor Il and the coils of relay 393 is connected to the other side of the line through conductor I". In this circuit closing o! push button 334 causes a current to iiow through the coils of relay 398 thereby energizing said relay and causing'short circuiting bar B to be thrust forward against contacts 4I2 and 4M, whereupon-push button 39| becomes inactive and maybe released.

In this manner a circuit is established fromV a source of current through switch 382, conductor 400, thermal switch 333, conduits 408, contacts I2 and 4M, conductor "I, the coils of electrical magnetic valve 320 and conductor 406 to the other side ofthe line. Energizing this circuit by push- 334 causes valve 320 to open. 'I'his valve will remain open until the circuit is broken by thermal switch 333.

Operation. of the apparatus establishes Joint temperature and viscosity control of various types of given reactions. The supply of steam may be varied in response to viscosity by means of valve 322 and the temperature `may be controlled by valves 320 and 326 in accordance with thermal requirements. Thermal switch 386 comprises two switches similar to thermal switches ISIA and I 54B described with reference to Figure 3. Hence, when thermal requirements reach a certain point the direct supply of steam is cut oiI by closing valve 320 of Figure 5, thus breaking the circuit through relay 390 and causing an, indirect supply of steam to be admitted through valve 326. At the same time both the direct and indirect steam supply are controlled in response to viscosity by valve 322; i

As a speciilc and original use of the apparatus described in Figure 1 we cite the following example of its application to the enzyme conver-Y sion of a starchy product, a process which normally requires much experience and close supervision.

Example A suitable kind and quantity of an `amylase is added to the desired concentration of a starch` slurry in a tank equipped with an agitator and suitably heated. The apparatus of our invention is connected to the tank so as to circulate an approximately constant volume of the slurry. Heating of the slurry is begun and the diaphragm of our controLdevice is weighted so as to shut oil the heating automatically when the circulating paste reaches any given viscosity. In this manner the amylase is allowed to degenerate the gelatinized starch, thinning it as it gelatinizes. When thin enough, the diaphragm co1- lapses and heating is resumed until the viscosity increases suillciently to distend the diaphragm and again to'shut of! the heat. In this manner, and particularly with high solid concentrations, the input of heat proceeds by a series of automatically controlled steps, preventative of agitation dimculties and the slippage of pulleys, until the starch conversion product becomes too fluid to operate the diaphragm under its initial external loading. 'I'he temperature of the circulating fluid then is allowed to rise to the optimum converting temperature of the amylase when the l .as close as possible viscosity starch conversion claim as new and heat input is thermostatlcally shut oil, a visible and/or audible signal is given and the `operator teststhe viscosity of the liquid gum. It the viscosity is still above the desired degree, the diaphragm is then reset under a light external load, once again expanding it. and stopping further input of heat until thinning proceedsto the desired degree. At this point the ilnal collapse of the diaphragm actuates an audible and/or visible signal, and if the viscosity has reached the desired degree, the operator then inactivates the amylase. Once this final weighting of the diaphragm has been determined by experiment, further conversions proceed with minimum operating attention. l

The above example is cited only by way of specific illustration of one oi' the commercially useful applications of the combinations of controls comprising the apparatus of our invention and is not to be understood as in any way limiting its scope. The various uses to which starch and its derivatives are applied usually require A or consistency controL Our combination of controls is easily adaptable to any substance capable of viscous or plastic ilow and varying in viscosity or plasticity as a function of temperature or dilution. While especially applicable to starchesand starch derivatives, the invention may also be employed in processing oils, fats, paints, glues, chemicals, etc.

Having thus described the invention, what we i desire to secure by Letters Patent of the United States is:`

1. A viscosity controlled regulating apparatus for carrying out a starch conversion reaction characterized by a variation in viscosity comprising, in combination, a reaction chamber for holding a starch conversion reaction mixture, means for circulatingat least a portion of said reaction mixture through a pump, a `torque mechanism operatively associated with said pump and responsive to changes in viscosity of said circulating reaction mixture, and meansresponsive to the operation of said torque mechanism to cause said starch conversion reaction to be controlled according to changes in viscosity.

2. A viscosity controlled regulating starch conversion apparatus comprising, in combination, a chamber for holding a starch conversion reaction mixture, means comprising an external circulating system for withdrawing a portion of the reaction mixture from one part o1' the chamber and returning it to another part of said chamber, al pump in said external circulating system adapted to circulate the starch conversion reaction mixture through said system during the course of the starch conversion reaction while maintaining substantially non-pulsating ilow, a viscosity responsive means associated with said pump, and means controlled by .said viscosity responsive means to cause said starch conversion reaction to be controlled according to variations in viscosity.

3. A viscosity controlled starch conversion regulating apparatus comprising, in combination, a reaction chamber for holding a liquid phase starch conversion reaction mixture, an outlet in the lower part of said reaction chamber, an inlet in the upper part of said chamber, circulating means for withdrawing a conilned stream of-said mixture from said outlet and returning it to said inlet, a viscosity responsive means operatively associated with said circulating means, and means controlled in response to `said viscosity responsive means to cause said starch conversion reaction in said main reaction chamber to be controlled according to variations in viscosity.

. 4. A viscosity controlled starch conversion regulating" apparatus comprising, in combination, a reaction chamber for holding a liquid phase starch conversion reaction mixture, circulating means for withdrawing a conned stream of said starch conversion mixture from one part of said reaction chambe`r and returning it to another part of said chamber, said circulating means comprising a pump. a viscosity responsive mechanism operatively associated with said -pmp actuated in response to variations in the viscosity of the circulating reaction mixture, and means controlled by said viscosity responsive means to cause saidstarch conversion reaction to be controlled according to variations in viscosity.`

5. A viscosity controlled liquid phase starch conversion regulating apparatus comprising, in

combination, a reaction chamber for holding a liquid phase starch conversion reaction mixture,

circulating means for circulating a portion of the reaction mixture in a confined stream from one part oi said react-ion chamber to another `out of Contact with the main reaction mixture,

changes in the viscosity of the circulating relicy l tion mixture, adjustable means associated with said viscosity responsive device to cause the same to be actuated only at a predetermined 'viscosity of said circulating reaction mixture, and means controlled by said viscosity responsive device t'o cause said starch conversion reaction to be controlled when `said predetermined viscosity is attained.

THOMAS D. THOMPSON. GEORGE V. CAESAR. 

